New efficient CW far-infrared optically pumped CH2F2laser

Far-infrared laser action is reported for the first time from the optically pumped CH2F2molecule. Lasing on twelve FIR transitions was produced by pumping with six emission lines in theRbranch of the 9.6 μm band of the CW CO2laser. High conversion efficiencies of up to 20 percent of the quantum limit have been obtained with the stronger FIR laser lines.     

New CW FIR laser action by Stark tuning from optically pumped CH3OH and CH3OD

Fifteen new CW FIR laser lines are reported from Stark tuned CO2optically pumped CH3OH and CH3OD. Four new CW laser lines have also been observed from zero field optically pumped CH3OD, three with a CO2laser, and one with an N2O laser.     

Continuous-wave CH3F waveguide laser at 496 µm: Theory and experiment

The kinetic processes controlling the conversion of CO2pump radiation into far-infrared (FIR) radiation in optically pumped waveguide lasers are discussed. It is found that pump saturation and excited-state FIR absorption play major roles in limiting the conversion. Good agreement between theory and experiment was obtained over a wide range of pump powers, gas pressures, and mirror reflectivities. For a well-optimized system, power-conversion efficiencies of 0.2-0.6 percent can be realistically achieved for CH3F.     

Observation and assignment of large offset farinfrared laser lines in CH3OH optically pumped by a CO2waveguide laser

Four new FIR laser lines at 62.98, 48.77, 224.53, and 190.65 μm are reported from CH3OH, optically pumped by the 10R34 and 9R10 lines of a waveguide CO2laser. Measurements performed by several techniques confirm that the pump offsets are outside the tuning range of conventional CO2lasers. Two of the lines are assigned as highJtransitions within the torsional ground state of the CO stretch.     

New optically pumped CW submillimeter emission lines from OCS CH3OH and CH3OD

A new emission line has been observed by optically pumping OCS with 9 μm R(8) CO2laser radiation and has been tentatively assigned. In addition, fourteen new emission lines of CH3OD and four of CH3OH have been discovered.     

New far-infrared laser lines from CO2-laser-pumped CH3OH gas by using a copper waveguide cavity

Eleven new far-infrared (FIR) laser lines have been observed from CH3OH pumped by a CO2laser. These lines are ranged from 78 to 694 μm and are obtained by using a copper waveguide cavity.     

Analysis of CH3OH far infrared laser lines optically pumped by sequence band and isotopic CO2lasers

Assignments are presented for seven far infrared (FIR) laser lines of CH3OH pumped by theS-9P(31),18-10R(24),13-9R(26), and13-9P(16)CO2laser lines, plus an interesting speculation for the FIR line pumped by the18-9P(12)CO2line. Frequencies have been deduced to a substantially improved accuracy of ±0.001 cm^-1from IR and FIR spectroscopic combination differences for most of the assigned lines as well as three other predicted transitions. In addition, accurate frequencies are given for 13 predicted FIR laser transitions which are expected from the IR spectrum to be pumped by three¹⁶O¹²C¹⁸O laser lines.     

Far infrared laser lines in CH3OH, optically pumped to CO stretch states and to strongly interacting vibrational states

A commented table is presented, containing 90 assigned FIR emission lines of the CH3OH laser, which can be dixectly or indirectly related to the torsional ground state of the CO stretch. Based on a model, which empirically takes into account interactions with other vibrational modes, the table compares measured and calculated pump and emission frequencies. For 14 pump transitions withJ leq 26, the rms deviation is 0.005 cm^-1. For 26 FIR emission transitions involvingJ leq 26, where the accuracy of the model can be checked against frequency measurements, the rms deviation is 0.004 cm^-1. Pump transitions to a strongly perturbing mode are identified, and accurate energy level parameters for this mode are given.     

FIR laser lines of CH3OH pumped by CO2laser sequence lines

We report on the utilization of a sequence band CO2laser as the pumping source for new FIR laser lines of CH3OH.     

Collisional narrowing in the optically pumped CH3OH and CH3F lasers

The gain linewidth of the optically pumped CH3F laser is observed to narrow and rebroaden with the addition of He. In addition, we observe the same effect in the CH3OH laser with the addition of the polyatomic buffer gases SF6and CS2. These results offer conclusive evidence of the Dicke narrowing phenomena in these inverted pure rotational transitions. The effect is observed using a high harmonic mixing technique in a Schottky barrier diode.     

Assignments of the high power optically pumped CW laser lines of CH3OH

Thirteen far IR laser lines in CH3OH, optically pumped by a CO2laser, have been assigned toa- andb-type transitions in ν5CO-stretch band. Identification procedures used were: a frequency match between the CO2pump and CH3OH absorption, frequency match of laser lines and CH3OH ν5transitions, polarization of far IR radiation, cascade and competition effects between far IR laser lines, and frequency consistencies. An improved set of molecular constants for ν5transitions were also obtained.     

Stimulated Raman scattering of picosecond light pulses in hydrogen, deuterium, and methane

Experimental results are presented on stimulated Raman scattering of short pulses of approximately 100 ps duration in H2, D2, and CH4, both in capillary waveguides and in a tight focusing geometry. Experimentally determined thresholds are in good agreement with calculation. Low thresholds (< 20 muJ) are observed in CH4and preliminary results using a mode-locked dye laser as pump indicate a useful source of tunable short pulse radiation in the near infrared.     

Efficiency of a high pressure CO2laser pumped CH3F Raman laser

An experimental investigation of the conversion efficiency of a high pressure CO2laser pumped CH3F Raman laser is reported. We show that resonance absorption of the CO2laser radiation in the CH3F gas can lead to a severe limitation of the efficiency. At CO2laser frequencies where the stimulated Raman action is strongest, a quantum efficiency for conversion of CO2laser radiation into far infrared radiation of the order of 0.1 is observed.     

Assigment of the CH2F2laser lines associated with the 9R(34) CO2pumping transition

Two new submillimeter laser transitions are reported for CH2F2optically pumped by the 9R(34) CO2line. The new transitions allow us to assign molecular transitions to the complete group of laser lines observed with that pump transition.     

New FIR laser lines from optically pumped CH3OH: Measurements and assignments

26 new FIR laser lines have been observed in CO2laser pumped CH3OH, and together with some previously observed lines their wavelengths have been measured with a relative accuracy of3 times 10^{-4}by using the FIR resonator as a scanning Fabry-Perot interferometer. Based on the internal consistency of the data, it is suggested that a number of the lines originate from combination bands involving simultaneous excitation of the CO stretch mode and a different vibrational mode.     

The temperature dependence of the CH3F far infrared laser output

The output power of an optically pumped far infrared waveguide laser has been measured for the laser gas CH3F between -100 and +100°C. At -30°C, an enhancement by a factor of about 3.5 over room-temperature operation has been found. The experimental data are compared with a recent theoretical treatment; the output power drops more rapidly than predicted towards both high and low temperature.     

Submillimeter laser action of CW optically pumped CD2Cl2, CH2DOH, and CHD2OH

More than 30 laser lines, several of them with an intensity in the order of mW have been obtained in the submillimeter wavelength range from 100 to 900 μm by optically pumping the deuterated molecules of dichloromethane (CD2Cl2) and methanol (CD2HOH, CH2DOH) with a step tunable CO2laser.     

Millimeter and submillimeter-wave laser action in symmetric top molecules optically pumped via perpendicular absorption bands

Ninety-nine new far infrared (FIR) laser lines from 227 μm to 1.965 mm have been observed in CH3CN, CH3CCH, CH3Cl, CH3Br,and CH3I by optically pumping these gases with CO2-laser pulses of 150-μs duration.     

Narrow bandwidth emission from a mirrorless, far infrared, 13CH3F laser

Frequency tuning and linewidth measurements are reported for a pulsed, mirrorless, kilowatt-power-level, far-infrared (FIR) ¹³ CH₃F laser operating at 245 GHz. The pump laser is an etalon tunable, single-mode CO₂ TEA laser. The FIR frequency spectrum was measured with 2.5-MHz resolution on individual 100-ns laser output pulses using harmonic mixing techniques. The linewidth of the amplified spontaneous emission was found to be surprisingly narrow, about 15 MHz. Frequency tuning of the FIR laser, as the pump laser frequency is tuned, is nonlinear, possibly due to inhomogeneous broadening of the gain by the K-level substructure of the rotational states. These results indicate that heterodyne receivers capable of single-shot frequency measurements can be important tools for investigating the properties of Raman FIR lasers     

A high-intensity narrow bandwidth pulsed submillimeter laser for plasma diagnostics

A CH3F laser oscillator producing between 0.5 and 1 kW pulses lasting 400 ns and confined to less than 27-MHz bandwidth at 496 μm is the basis of an injection laser assembly which generates up to 250 kW of far-infrared (FIR) output within a bandwidth of 55 MHz.